Source Citation

Abstract

Objective

To determine whether the identification of patients who are likely to breathe spontaneously
and subsequent feedback to physicians will promote earlier discontinuation of mechanical
ventilation (MV) and reduce mortality, length of stay, costs, and complications.

Design

Randomized controlled trial.

Setting

Medical and coronary intensive care units (ICUs) of a U.S. teaching hospital.

Patients

300 nonsurgical patients (mean age 61 y, 50% men) with respiratory failure. Exclusion
criteria were age < 18 years, dependence on MV for ≥ 2 weeks, or existence of
an extubation order. Follow-up was complete.

Intervention

Daily screening of all patients (n = 149 in the intervention group, and n = 151 in the control group) was defined as positive if all of the following occurred:
ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen
> 200; positive end-expiratory pressure ≤ 5 cm of water; adequate cough during
suctioning; ratio of respiratory frequency to tidal volume of < 105 breaths/min
per liter (rapid, shallow breathing); and only intermittent use of sedatives or low-dose
dopamine. Patients in the intervention group with a positive screening test were given
a 2-hour trial of spontaneous breathing. The results of this trial, if successful,
were given to the attending physicians in person or by telephone.

Main outcome measures

Duration of MV, time from a successful screening test to discontinuation of MV, and
length of stay in the ICU. Secondary outcomes were death, hospital costs (U.S. dollars),
length of hospitalization, and complications (need for reintubation within 48 h, removal
of breathing tube by patient, tracheostomy, and MV for > 21 d).

Conclusion

Daily screening of respiratory function with trials of spontaneous breathing for appropriate
patients reduced the duration of MV and cost of intensive care in patients on MV but
not total mortality or total hospital costs.

Commentary

Ely and colleagues notified physicians of patients in the intervention group who were
deemed ready for ventilator weaning after tolerating a 2-hour trial of spontaneous
breathing. Physicians who attended patients in the control group were not notified
and therefore made the decision to begin weaning without this information. Simply
notifying the attending physicians in the control group when patients met the screening
criteria might have resulted in much more comparable outcomes in the groups. Further,
although patients in the control group were screened, they did not have early spontaneous
breathing trials. Esteban and colleagues (1) showed that daily spontaneous breathing trials resulted in more rapid discontinuation
of MV than pressure support or intermittent mandatory ventilation styles of weaning.
Thus, control group patients in the Ely study did not have the early "kick start"
of spontaneous breathing trials.

Inexperienced physicians often have a great desire to begin weaning early in a patient's
clinical course by decreasing the intermittent mandatory ventilation or pressure support
ventilation. However, experience teaches that, although weaning may begin immediately
or in 1, 2, or 6 days, success comes on the day that the clinical condition of the
patient allows it, regardless of when the process starts. Patients with acute respiratory
failure do not depend on us to wean them—they depend on us to treat their underlying
illness and discontinue MV when appropriate.

In my view, screening of patients by the nursing and respiratory staff on a daily
basis should become a routine part of the care of patients with acute respiratory
failure. These professionals can then advise us that clinical conditions may permit
discontinuing MV earlier than if we were left to our own devices.